This invention relates to indexing apparatus, and more particularly to a geneva index positioned dial index table of superior accuracy, as well as to a unique method of aligning same.
Index tables for holding workpiece fixtures and indexing them past sequential machinery operations must be capable of accurately positioning each station thereon in the exact angular location the machining apparatus expects to find it. If this does not occur, inaccurate machining may result. Achieving this increasing need for accuracy has become very difficult, especially in the larger index tables, such as those up to seven feet or more in diameter. Traditionally it has been very hard to avoid accumulating angular errors in the gauging and aligning such equipment. Furthermore, many such alignment techniques require at least partial disassembly of the machine (such as removal of the index table), and often subsequent reassembly introduces new errors into the machine.
It is therefore an object of the present invention to provide an improved index table which is capable of being very simply aligned with extreme accuracy, as well as a method of achieving this accuracy using a laser transmitter/receiver and a gauging prism, in combination with eccentric locating pins. While it has been known to use laser equipment and eccentric pins, the present invention is unique in that it can be practiced with the machine in fully assembled running condition, using the actual machine drive, thus avoiding the possibility of introducing additional errors or inaccuracies into the machine during disassembly and reassembly. The result is much greater accuracy than could be machined into the index table, e.g. less than 0.001" cumulative deviation around the entire periphery of the table.